The present invention relates to a silage cutting implement.
The present invention relates to a silage cutting implement according to the preamble part of claim 1.
Due to the current problems of keeping cattle a trend has developed towards extremely large cattle farm or to very small cattle farms. Extremely large cattle farms, e.g. in France, frequently employ large working vehicles like wheel loaders which allow to manipulate different tools, even silage cutting implements. Small cattle farms tend to employ cutting implements as well, because large combined cutting and mixing aggregates are costly and cannot be used efficiently enough. For that reason there is a significant demand for powerful silage cutting implements.
In a cutting implement known from DE 299 20 834 U which is to be mounted to the front or rear of a tractor, the hydraulic cylinders are supported behind the frame structure of the lower part of the equipment at low positioned linkage points. The upper linkage points are located at outriggers which are cantilevered rearwards from the frame of the upper part of the implement. Because the hydraulic cylinders are retracted when the cutting implement is fully opened, they have to have a structurally limited cylinder length which limits the vertical silage taking range of the fully opened cutting implement. Since the lever arms between the hydraulic cylinders and the pivot axis are very short in relation to the lever arm of the cutting edge of the upper part of the implement neither high cutting forces nor a uniform cutting movement can be achieved. The described design principle can be found in practically all cutting implements which have been available for at least thirty years on an up to now small market. The available cutting implements vary from each other only in details and are designed like two-part excavator shovels and are driven like them. However, the known cutting implements are not able to properly cut out a slice over the full height of the silage block which nowadays in the farming industry is usually as high as 2.2 m or more. The known cutting implements take only a relatively small portion from the silage block, i.e. a bit. A continuous slice, however, is extremely expedient in view to the quality and the form of the cutting surfaces in the silage block, the quality and homogeneity of the fodder formed by mixing the slice, and the loss free and comfortable consumption of silage blocks of differing heights and/or forms, and in order to improve the acceptance of such cutting implements on the presently positively developing market.
In a cutting implement of this kind (EP 05 62 542 A) the hydraulic cylinders are positioned inside in the loading area of the cutting implement. As soon the hydraulic cylinders close the filled cutting implement they are pivoting into the silage charge. The distances of the linkage points of the hydraulic cylinders to the pivot axis are extremely different and increase the danger of an unstable cutting operation and of distortions particularly of the upper part of the implement.
The hydraulic cylinders controlling the silage cutting operation of a self-propelling fodder mixer aggregate (DE 29 916 030 U) are positioned behind the lower loading shovel which temporarily takes the separated silage slice before it transfers its load into the mixing chamber.
Further prior art is contained in DE 43 32 267 A, FR 27 54 671 A, EP 05 99 151 A, FR 27 73433 R, GB 20 87 206 A, EP 05 06 158 A.
It is an object of the invention to provide a powerful silage cutting implement which suits to the manipulating capacity of modern working vehicles, which has a vertical silage gripping range corresponding with the full height of silage blocks as are usually found in farming practice and which allows a clear, powerful cut and the separation of a slice which continuously extend over the full height of the silage block.
Thanks to the hydraulic cylinders provided between the pivot axis and the active cutting edge, which hydraulic cylinders are retracted during the cutting operation, not only an extremely high silage taking range corresponding to the usual heights of silage blocks can be obtained but also a powerful and smooth cut with high cutting force and advantageous lever relationships. The intended deviation from usual concepts of silage cutting implements matches with modern, powerful working vehicles and connection assemblies allowing to optimally use the advantage of the large silage taking range, to achieve an expedient cutting surface form and cutting surface quality in the silage block and to prepare fodder of high quality from the separated slice. Normally, the farmer or rancher holds working vehicles of modern design and by far sufficient efficiency useful also for other work. Similar drive concepts exists at large, ground borne combined silage mixing and cutting aggregates for which other prerequisites are true which cannot be compared to the prerequisites of such simple silage cutting implements. Such long hydraulic cylinders when extended allow to obtain the desired high silage taking range and can be positioned comfortably between the angled sections such that they can use the largest interior width of the closed cutting implement. Advantageous active lever arms result if the frame structure has prolongations gripping beyond the side walls of the lower part of the implement in which prolongations the pivot axis is located. The hydraulic cylinders located at the outer sides of the cutting implement need not get in contact with the silage block since only slices with limited cutting depth are cut out.
Expediently the distance from the pivot axis to the linking point at the lower part of the implement is larger than the distance from the pivot axis to the linking point at the upper part of the implement. This increases the silage taking range and leads to high cutting forces resulting in a proper and smooth cut.
In practice frequently silage blocks exist of a height of at least 2.2 m, or even higher, the distances or lever arms as selected for the design of the cutting implement and of its driving components should be matched with each other such that a cutting or silage taking range is obtained which amounts in vertical direction to at least 2.2 m, preferably up to 3.0 m, more preferably even up to 4.5 m. The closed cutting implement, however, has a comfortable handling size and a weight which can be manipulated easily by wheel loaders, modern tractors or front loaders.
To transmit the high cutting forces without problems into the parts of the cutting implement it is recommendable to provide stiffening parts forming protecting and pocket-shaped sockets for the linkage points of the hydraulic cylinders. The stiffening parts, furthermore, serve to enforce the parts of the cutting implement and of the load sensitive angled sections. The stiffening parts allow, furthermore, to position the linkage points as low and as high, respectively, as possible to use hydraulic cylinders of large cylinder length.
As the separated slice has to be transported in the closed cutting implement to the disposal, it is expedient to form the frame structure at least of the lower part of the implement as a closed rear wall which prevents that silage falls out and which contributes to the overall stability.
As the high silage taking range and the strong cutting forces could be accompanied by distortions of the parts of the cutting implement causing damage or operation disturbances, not only a, e.g. hydraulic, synchronisation control of the hydraulic cylinders is provided, but in addition an, e.g. electromechanical, sensing device for relative-distortions is provided to assist the synchronisation control. Conventional hydraulic synchronisation controls, e.g. employ serially connected hydraulic cylinders of differing cross-sectional areas of which the bigger one is actuating by its piston rod side pressure the piston side end of the smaller one, or parallel flow controlled hydraulic cylinders of equal dimensions by means of a flow divider or a flow regulating device. However, in practice these operate with tolerances of several percent and can for that reason not reliably exclude distortions finally leading to a blockage. Even conventional mechanical synchronisation controls are not reliable enough. The additional, e.g. electromechanical, sensing device apt to overrule the synchronisation control in case of a too strong distortion, however, helps to avoid damages and even may interfere intentionally to eliminate distortions as soon as they tend to occur.
In a structurally simple manner the sensing device is equipped by two linkage mechanisms provided at both sides of the cutting implement which linkage mechanisms have a mutual mechanical coupling for the actuation of a signal generator in case that a not tolerable deviation occurs between the respective pivoting angles, e.g. of the upper part of the cutting implement, at both sides of the cutting implement. Expediently the signal generator generates an alarm signal and/or a switch off signal and/or a correction signal for the synchronisation control. The alarm signal may be used to reduce the cylinder actuation forces and to check the situation. The switch off signal may interrupt the cutting operation for safety reasons. The correction signal can be used to intentionally interfere hydraulically until both hydraulic cylinders again are synchronised and work with equal lengths.
The linkage mechanisms of the sensing device expediently employs two first links bridging the pivot axis, two sensing links, one of which rotates the coupling shaft, and a reference lever detecting the angular displacement between both sensing links and actuating a signal generating switching device in case that a distortion is detected which cannot be tolerated.
A smooth, gradual interference of the sensing device is possible if the reference lever is controlled by a flexible switch actuating tongue.
The switching device expediently contains two alternatingly actuatable limit switches, e.g. electric microswitches, informing the synchronisation control by generated signals which of the cylinders is leading or is trailing. Then the synchronisation control can interfere in a correcting sense.
In order to achieve a proper cut, to avoid disturbing friction loads and to rapidly transfer the separated slice into the interior of the cutting implement, it is expedient to form the separating plane with an arcuate curvature. The cutting knife at the lateral edge of the separation plane may be a fixed stationary cutting knife or even may comprise cutting knives which can be driven oscillatingly.
Furthermore, also at the free edge regions of the side walls in the parts of the cutting implements, expediently only adjacent to the lateral edges, cutting knives ought to be provided, either stationary knives or blades or moveable knives, in order to properly form the side edge regions of the slice and/or to cut through the plastic foil which protects the silage.
In order to place the cutting implement close to the centre of gravity of the working vehicle, the cheeks of the frame structure carrying the vehicle connection assemblies should be spaced apart more than the width of the vehicle or the width of the vehicle cabin. Then the vehicle can be brought between the cheeks and close to the frame structure in order to achieve advantageous lever relationships for lifting the cutting implement and for travelling with the filled cutting implement.